If you plan on overclocking then OCZ are good, just get Platinum Rev 2s or something. Corsair are good, Crucial Ballistix are good, Geil, GSkill, any of those are going to be pretty good RAM. Just don't get like value ram try to stick with higher end stuff.

Others may have different suggestions, but you will be pretty safe with any of those.

EDIT: If you are using the 800Mhz Reapers then maybe you will be fine. I got the 1150Mhz sticks and so compatibility is not as good.